Many processes and devices have been used in the field of pressure sensing. Pressure sensors are generally used and deployed wherever a need for monitoring and responding to pressure changes is necessary. Pressure sensors are commonly used in a variety of automotive, aerospace, commercial, industrial, and consumer applications.
The operational environments in which pressure sensors are required to operate in these applications with high accuracy and repeatability can be very demanding. For example, extreme thermal conditions including thermal shocks in ranges from 150 C to −55 C, and extreme conditions of shock and vibration.
Pressure sensors may typically include a substrate, a silicon pressure sense die with a diaphragm movable in response to pressure programmable compensation IC die, a cover to enclose the diaphragm, and terminals extending through some part of the base or cover to supply power and to measure a pressure signal. The programmable compensation IC die can be utilized for adjusting the output of the sensor die to obtain the pressure signal. In such a configuration, wire bonds can be utilized to provide an electrical connection between bonding pads on a top surface of the silicon sense die and compensation IC die and conductor paths on the ceramic substrate.
In the majority of prior art applications, the silicon pressure sense die is bonded to the compensation integrated circuit die by bonding each die separately to the ceramic substrate and utilizing traces on the substrate to connect the two die. Hence, these wire bonds require area on the ceramic substrate for bond pads which increases the number of the wire bonds. Two wire bonds, with an intervening conductive trace on the ceramic substrate are required to make each connection between the pressure sense die and the programmable compensation IC. The inductance of the connective path increases as the length of the path increases. The increase in the number and length of the wire bonds further increases package size and manufacturing cost. Further, the reliability of the sensor can also be affected by the number of wire bonds required. In general, it is desirable to reduce the length and number of the wire bonds and conductive traces utilized to connect the pressure sense die wire bond pads to the compensation integrated circuit die.
Based on the foregoing it is believed that a need exists for an improved method for direct die-to-die wire bonding. It is also believed that a need exists for an improved pressure die pad layout that is compatible with different compensation integrated circuit dies.